Gridded seismicity updates

Subsequent to publication of Petersen et al. (2023) several issues were identified in the gridded seismicity model:

• Higher PGA and short period hazard in south-central Utah than along the Wasatch. Solution: use WUS and CEUS GMMs with 50% weight each in the transition zone between the attenuation boundary and -104°.
• Higher hazard at other CEUS sites due to changing weights on smoothing kernels (there are numerous other changes from 2018 to 2023 in the gridded seismicity model that are justified by improved modeling methodologies, but changing the smoothing kernel weights was only done to make the CEUS consistent with the WUS and absent further discussion we think these should remain the same as in 2018). Solution: Revert smoothing kernel weights to their 2018 values.

added 2023 ERF GMM Hazard-Disagg labels

assigned to @pmpowers

marked the checklist item Higher hazard at other CEUS sites due to changing weights on smoothing kernels (there are numerous other changes from 2018 to 2023 in the gridded seismicity model that are justified by improved modeling methodologies, but changing the smoothing kernel weights was only done to make the CEUS consistent with the WUS and absent further discussion we think these should remain the same as in 2018). Solution: Revert smoothing kernel weights to their 2018 values. as completed

marked the checklist item Higher PGA and short period hazard in south-central Utah than along the Wasatch. Solution: use WUS and CEUS GMMs with 50% weight each in the transition zone between the attenuation boundary and -104°. as completed

mentioned in merge request !121 (merged)

mentioned in commit 6a0b97c9

closed with merge request !121 (merged)

Reopened. Per discussion with Mark we're going to 2/3 NGA-West2 and 1/3 NGA-East in the transition zone.

reopened

Resolved in !122 (merged)

closed